Copy Link to Text: Add to fieldtrial_testing_config.json

Bug: 1105862
Change-Id: I84b07861bf1cc6485a07546347154e6cb9262c53
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2443214Reviewed-by: Brian White <bcwhite@chromium.org>
Commit-Queue: John Lee <johntlee@chromium.org>
Cr-Commit-Position: refs/heads/master@{#819072}

testing/variations/fieldtrial_testing_config.json

@@ -1879,6 +1879,24 @@
             ]
         }
     ],
+    "CopyLinkToTextDesktop": [
+        {
+            "platforms": [
+                "chromeos",
+                "linux",
+                "mac",
+                "windows"
+            ],
+            "experiments": [
+                {
+                    "name": "Enabled",
+                    "enable_features": [
+                        "CopyLinkToText"
+                    ]
+                }
+            ]
+        }
+    ],
     "CrOSMinFilelistKB": [
         {
             "platforms": [